So yeah. xD
I just got Noire in Fire Emblem and I fell in love with her! I immediately decided I wanted to cosplay her, but then I realized she would be my first armor project. I've never worked with any of it, ever. That being said, I don't know anything about any of the materials. I sew, I don't craft..
If anyone can explain to me thoroughly what they think is appropriate for the armor (mostly the arm piece, boots, and bow), i'd be greatly, greatly appreciative!

Sewing patterns, yes. I've read tutorials, but it's all very daunting to me, I simply don't get it.
I'm confident that I can get the sewing part of it just fine, but the arm guard and the bow are intimidating at best...

Armour patterns are pretty much the same theory as fabric patterns. Think of a top with princess seams - you're using a flat pattern to make a 3D object. In armor you just have the use of a bit more flexibility in your material and it being able to retain shape in a curve instead of buckling to an extent.

The only armor piece I really see in the reference is the arm thing. The calf-protectors look like pieces of perforated leather. For the arm thing you're really looking at a lot of rectangular pieces to wrap around the arm, held together by joints or something else with circular pieces around them for decoration. I can't see what's going on at the shoulder well, but it looks like some rectangles with pointed ends, basically. Not sure if the elbow is functional or what, either - I'd want to find more reference pictures if I was making a pattern. A good shot of it from the side would help.

It's really just like sewing and making sewing patterns. Think, "what do I have to do to make this 3D" ? Think about what shape it will have to be when it's flat. You start with making your pattern out of cardboard or even construction paper - just like you'd make a toile of a fabric costume out of muslin.

Unfortunately when it comes to armor that someone just drew from imagination it's often times impractical/nonsensical - so you have the challenge of making it work best in real life.

And instead of sewing seams you're usually working with joints, glue, or elastic - but they're not any harder than seams, and in fact I think they're easier !

I would not classify the bow as armor because prop-making, while you can apply pattern-making to it to an extent is pretty different. You're usually building up from a base or you're doing something entirely different like creating a form and casting and molding (which can be done for armor, too but is less common - more for things like mechs).

Whoops, I actually didn't mean to type the bow into reference! Thank you for typing that though, that's actually given me confidence that it's not much different than sewing, you just change the materials.
The only problem I have now is lack of knowledge to know how to make things like foam look relatively legitimate..
Ah well, I feel like I can give tutorials another shot now, thank you so much Kelley! (:

Honestly, the best way to make armor look legit (in my opinion) is the paint job. Even a rough piece of armor can shine with good paint. Look up weathering techniques. Exaggerating the light and shadows on a piece can give it a better look than just trying to make to foam look like smooth metal. The entropyhouse tut. Midnight Dawn linked to has a mini weathering section you can look at. I suggest googling Kamui Cosplay for an idea of what I mean about the exaggeration is sometimes better kinda thing. Kelley made some awesome points about armor being totally related to sewing (although armor comes way easier than sewing to me.) Don't be afraid to experiment with small pieces to see what works best for you, and have a blast!